Tunable Broadband Mems Fabry-Pérot Near Infrared Filter Based on Double-Membrane Silicon/Air Mirrors

We present a broadband tunable MEMS filter functional in a spectral range between 900 nm and 1650 nm. It is based on a double-membrane Fabry-Pérot interferometer (FPI) operating in first interference order comprising two symmetric Si/Air Bragg mirrors and a long range electrostatic actuation. The double-membrane approach allows optical gap and actuation gap to be separated, enabling independent adjustment of initial transmission wavelength and maximum mirror travel range. Additionally, this approach improves mirror parallelism. To our best knowledge, it is the first time an FPI based on Si/Air mirrors is tuned over the first order free spectral range unlocking the full potential of these high quality broadband reflectors.